You strip off all proteins on the cell surface by using a protease (an enzyme that destroys proteins). now, when you add a specific signaling molecule, the cell still responds. what is the most reasonable explanation of this?

This is because the receptor is in the interior of the cell

Explanation:

When a specific signaling molecule is added to a cell whose cell surface has been stripped off by proteins the cell still responds because the receptor is in the interior of the cell.

Receptors  are divided into two categories which are;

Signalling molecules are necessary for the coordination of cellular responses by serving as ligands and binding to cell receptors.

A type of signaling molecule are the small hydrophobic ligands which can directly diffuse through the plasma membrane and interact with internal receptors unlike the water soluble ligands. This is why the cell still responds after you strip off all proteins on the cell surface.

NOTE: Nitric oxide (NO) is a gas that also acts as a ligand, therefore it can pass through the plasma membrane of the cell and interact with receptors.

clumped distribution, because you'de have all of the population gathered in a relatively small are.

it's the most common because it provides protection and a mate for reproduction

example: humans, seeweed, cattles, etc.